//==============================================================================
//	
//	Copyright (c) 2002-
//	Authors:
//	* Dave Parker <david.parker@comlab.ox.ac.uk> (University of Oxford, formerly University of Birmingham)
//	
//------------------------------------------------------------------------------
//	
//	This file is part of PRISM.
//	
//	PRISM is free software; you can redistribute it and/or modify
//	it under the terms of the GNU General Public License as published by
//	the Free Software Foundation; either version 2 of the License, or
//	(at your option) any later version.
//	
//	PRISM is distributed in the hope that it will be useful,
//	but WITHOUT ANY WARRANTY; without even the implied warranty of
//	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
//	GNU General Public License for more details.
//	
//	You should have received a copy of the GNU General Public License
//	along with PRISM; if not, write to the Free Software Foundation,
//	Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
//	
//==============================================================================

package com.prism.e4.rcp.parser.visitor;

import com.prism.e4.rcp.parser.EvaluateContext;
import com.prism.e4.rcp.parser.ast.ExpressionConstant;
import com.prism.e4.rcp.parser.ast.ExpressionLiteral;
import com.prism.e4.rcp.parser.ast.ExpressionVar;
import com.prism.e4.rcp.prism.PrismLangException;

/**
 * Evaluate partially: replace some constants and variables with actual values.
 */
public class EvaluatePartially extends ASTTraverseModify {
	private EvaluateContext ec;

	public EvaluatePartially(EvaluateContext ec) {
		this.ec = ec;
	}

	public Object visit(ExpressionConstant e) throws PrismLangException {
		Object val = ec.getConstantValue(e.getName());
		if (val == null) {
			return e;
		} else {
			return new ExpressionLiteral(e.getType(), val);
		}
	}

	public Object visit(ExpressionVar e) throws PrismLangException {
		Object val = ec.getVarValue(e.getName(), e.getIndex());
		if (val == null) {
			return e;
		} else {
			return new ExpressionLiteral(e.getType(), val);
		}
	}
}

// ------------------------------------------------------------------------------
